Pruning can adjust the structure of pear population and individual parts, improve the utilization conditions of light energy, adjust the quantity, quality and rhythm of the formation of various organs in the tree, coordinate the contradiction between growth and fruiting, aging and rejuvenation, and balance the various parts and organs of the tree. Its main function is to regulate the relationship between fruit tree growth and fruit bearing. Now its function is described as follows:

(1) Adjust the relationship between fruit trees and environment

Pruning can adjust the individual and group structure of fruit trees, improve the utilization rate of light energy, create better microclimate conditions and use space more effectively. By shaping and pruning, the number of effective leaf areas can be increased and the lighting conditions can be improved. For sparse orchards, plastic surgery mainly considers individual development, attaches importance to the rapid use of space, reasonable crown structure and stress balance of each part, expands the crown as quickly as possible, has a large number of branches, is dense first and then sparse, has distinct layers, and has developed backbone branches and balanced stress. For the close planting garden, the plastic surgery mainly considers the group development, pays attention to adjusting the leaf curtain structure of the group, solves the contradiction between the group and the individual, tries to make the individual obey the group, has a short crown and few backbone branches, controls the crown to be too large, and realizes ventilation and light transmission.

(2) Adjust the local balance of the tree.

The normal growth of pear trees must maintain the relative balance of each part. Through shaping and pruning, the overall growth of fruit trees is adjusted by using the dynamic balance law of aboveground and underground parts. The aboveground and underground parts of fruit trees are interdependent and mutually restricted, maintaining a dynamic balance. The strengthening or weakening of either side will affect the strength of the other side. By pruning, the balance between them can be adjusted purposefully.

(3) regulating the relationship between vegetative growth and reproductive outcomes

The basic contradiction between growth and fruit runs through the life of pear trees and exists at the same time. Adjustment must be made through pruning, so that the two sides can reach a relative balance and create conditions for high yield, stable yield and high quality. When adjusting, we must first ensure that there are enough plant organs; Secondly, a certain number of flowers and fruits should be produced, which should be adapted to the number of vegetative organs. If there are too many flower buds, it is necessary to cut off flower buds or sparse flowers and fruits to promote the growth of branches and leaves to maintain the balance between the two types of organs; Third, we should pay attention to the relative independence of each part of the organ, so that some branches can grow and some branches can bear fruit, and they can be transformed alternately every year to achieve a relative balance.

(4) The dual functions of shaping and pruning.

That is, suppress the whole and promote the local. According to the difference of tree potential and age, pruning can not only promote growth, but also inhibit growth. For trees with vigorous growth and few flower buds, pruning can promote local growth, but because some vegetative organs are cut off, it will generally inhibit the growth of the whole tree and reduce the total growth of the whole tree. But for adult trees with many flower buds, pruning will cut off some flower buds and reduce nutrient consumption. Instead, it will increase the total growth and promote the growth of the whole tree.